The present invention relates generally to sub-systems of an electronic device, and more specifically, to a method and system for compensating for the effect of phase drift in a data sampling clock used in an electronic device.
An electronic device can include numerous sub-systems that transfer data between each other. For example, most electronic devices used in data/voice communication include a transceiver sub-system. A typical transceiver sub-system used in digital wireless communications includes, in addition to other elements, a Radio Frequency Integrated Circuit (RFIC) and a Baseband Integrated Circuit (BBIC). The RFIC and BBIC exchange data and control signals through a standard digital interface. This data is transferred frame by frame. Each frame consists of multiple data windows. Each data window consists of multiple data bits. The RFIC and BBIC use a data sampling clock to sample each of the received data bits. It is desired that the instance at which a data bit is sampled by the data sampling clock should be such that the data sampled is correct. At the start of each frame synchronizing data is sent by the sub-system sending the frame to acquire the instance at which data is sampled by the data sampling clock. Sometimes, the data sampling instance gets drifted due to jitter in a Phase-Locked Loop (PLL) attached to a clock generating unit of the electronic device. The jitter is a variation in the data sampling clock caused by variation characteristics such as interval between successive cycles, amplitude or frequency. This drift causes an error in the data sampled by the data sampling clock and also affects the bit error rate of the digital interface.
Currently, there are several methods available for compensating for the effect of phase drift in the data sampling clock, due to jitter in the Phase-Locked Loop (PLL). One of these methods samples data at three instances, namely, a bit sampling instance, an instance occurring prior to the bit sampling instance, and an instance occurring after the bit sampling instance. After sampling the data at these instances, the method compares the data sampled at the bit sampling instance and the data sampled at the instance prior to the bit sampling instance. The method also compares the data sampled at the bit sampling instance and the data sampled at the instance after the bit sampling instance. The result of this comparison is used to compensate for the effect of phase drift in the data sampling clock. However, this method is not accurate as data is sampled at minimal number of instances. Further, the method can be used only if you have multiple bits for quantization of the sampled data.